I am going to be redoing a floor in my house. The house is 25' wide, with an i-beam down the middle. The joists are 2x8's, 16" on center, the span is about 12 1/2' wide. I have plank sub-floor, 3/4" deep, about 8" wide that are installed at a 45 degree angle. The house is about 50 years old (1960 construction).
The floors are bouncy, and the planks are nailed in, so they squeak pretty good to. I am redoing a bedroom floor, and wanted to beef up the floor. Last year, I did a bathroom. I sistered the joists, and put down 3/4" T & G plywood. The sub-floor was replaced because the old one was rotting out. That floor is solid.
I plan on sistering the joists to stiffen the floor under the bedroom, but do I need to replace the plank sub-floor? Could I just screw it down? I know I could overlay with plywood, but then the floor height would not match in the hallway.